This document discusses ABB's OneFit retrofit solution for replacing aging circuit breakers. OneFit allows circuit breakers to be replaced with new technology while minimizing modifications to existing switchgear panels. It can be installed internally or externally with different package options. Key benefits include reduced downtime, improved safety, use of standard parts, and upgrading to current standards. OneFit offers flexibility in circuit breaker models and accessories and can serve as an intermediate solution until a full panel replacement is needed.